Total posts : 45366
From my experience as a Ham operator, I know you can be heard at great distances with little power when the time (propagation condition) is right.
I had a QRP (low power) transmitter, about 1/4 watt, known as The Tuna Tin Two. It was housed in a Tuna can and had two transistors, hence the name.
From Northeast Ohio I was able to make good contacts into Florida and Alabama. It operated in the 40 meter band (7 mHz) CW (Morse code.) Of course it’s easier to do on CW than voice.
The antenna was a horizontal half wave dipole, at 25 feet. The lead in was 100 feet of RG-59 (cheap) co-ax cable so if I got 75% of that 1/4 watt into the antenna I was lucky.
Although 1/4 watt into a dipole is a lot more than you’re allowed on the Part 15 13 mHz band, that 10,000 uV/m @ 30 m you are allowed could go a long way when the conditions are right.